From 38a0d0cdb46d3f91534e5b9839ec2d67be14c59d Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@c-s.fr>
Date: Wed, 14 Aug 2019 09:25:52 +0000
Subject: [PATCH] powerpc/futex: Fix warning: 'oldval' may be used
 uninitialized in this function

References: bsc#1065729
Patch-mainline: v5.4-rc1
Git-commit: 38a0d0cdb46d3f91534e5b9839ec2d67be14c59d

We see warnings such as:
  kernel/futex.c: In function 'do_futex':
  kernel/futex.c:1676:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return oldval == cmparg;
                   ^
  kernel/futex.c:1651:6: note: 'oldval' was declared here
    int oldval, ret;
        ^

This is because arch_futex_atomic_op_inuser() only sets *oval if ret
is 0 and GCC doesn't see that it will only use it when ret is 0.

Anyway, the non-zero ret path is an error path that won't suffer from
setting *oval, and as *oval is a local var in futex_atomic_op_inuser()
it will have no impact.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: reword change log slightly]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/86b72f0c134367b214910b27b9a6dd3321af93bb.1565774657.git.christophe.leroy@c-s.fr
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/include/asm/futex.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/futex.h b/arch/powerpc/include/asm/futex.h
--- a/arch/powerpc/include/asm/futex.h
+++ b/arch/powerpc/include/asm/futex.h
@@ -60,8 +60,7 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 
 	pagefault_enable();
 
-	if (!ret)
-		*oval = oldval;
+	*oval = oldval;
 
 	return ret;
 }
-- 
2.35.3